Animal studies have established that estrogen (E2) is a known cardio-protective hormone that helps recruit bone-marrow derived endothelial progenitor/stem cells (EPC) in the injured heart which, in turn, participate in the vascular repair of injured tissue. We and others have shown that E2-supplementation enhances the consumption of ethanol in ovariectomized (OVX) mice. However, whether alcohol/estrogen interactions alter the biology of EPCs or whether change in the microenvironment (alcohol) competes with the known beneficial effects of E2 on EPC-mediated myocardial repair is not known. The premise of our proposed research is based on our following published and preliminary observations: a) OVX mice receiving E2 (17b-estradiol) supplementation consume significantly more ethanol compared to those receiving placebo; b) E2-mediated re-endothelialization in denuded carotid arteries and E2-mediated neo-vascularization and blood flow recovery in ischemic hind limbs is blunted in mice consuming ethanol, despite E2 supplementation; c) in a mouse model of acute myocardial infarction (AMI) increased ethanol consumption following E2-supplementation reduces EPC mobilization and homing to ischemic tissues in eNOS and MMP9 dependent manner, depresses physiological and anatomical tissue repair and represses neo-vasculogenesis; d) in vitro, ethanol dose-dependently attenuates E2-induced proliferation, tubulogenesis and survival of both EPCs and mature endothelial cells (EC); interferes with genomic and non-genomic functions of estrogen receptors and switches the E2-mediated cell survival signaling to the induction of pro-apoptotic signaling. Our central hypothesis, therefore, is that increased ethanol consumption competes with E2-mediated post-infarct myocardial repair by negating the protective effects of E2 on EPC function and signaling. The experiments described in the current proposal are designed to extend these findings by testing a series of hypotheses grouped according to the following 3 specific aims: 1) Determine the role of individual estrogen receptors (ER) on ethanol-mediated repression of BM-EPC mobilization and post-AMI myocardial repair, 2) Define the role of eNOS and MMP9 in ethanol repression of E2-induced BM-EPC mobilization and function in post-AMI myocardial repair and 3) Elucidate molecular signaling involved in the ethanol-mediated suppression of E2-induced cell survival signaling pathways in EPC.